A locking mechanism

ABSTRACT

A locking mechanism  10  for a quick coupler A has a movable locking element  11.  A biasing element  13  is adapted to bias the locking element  11  to move in a first direction. An operator  12  is arranged to move the locking element  11  against the bias of the biasing element  13.  The locking element  11  has teeth or serrations  19  which, when the locking element  11  is moved by the biasing element  13  in the first direction, is engageable with further teeth or serrations  20  coupled to a movable wedge element F of the quick coupler A to lock the wedge element  11  against movement. The movement of the locking element  11  creates a compressive force that causes the teeth/serrations  19, 20  to positively mesh and remain meshed.

BACKGROUND OF THE INVENTION

This invention relates to a locking mechanism for a quick coupler.

Quick couplers for mounting an attachment, e.g. a bucket, to an earthworking machine such as an excavator are known. It is also known tohydraulically operate the quick coupler. A potential danger with anhydraulically operable quick coupler is that in the event of hydraulicfailure the quick coupler can fail to retain the attachment in a workingposition. For example, the coupler can fail to hold the attachment atone of the mounting points with the result that the attachment can swingdown from the coupler. The consequences of this can be injury to ordeath of someone in the vicinity of the attachment when the couplerfails.

SUMMARY OF THE INVENTION

An object of the present invention is thus to provide a lockingmechanism for a quick coupler whereby an attachment mounted by the quickcoupler is retained in a working position on the coupler in the event ofhydraulic failure or to at least provide the public with a usefulchoice.

Broadly according to one aspect of the invention there is provided alocking mechanism for a quick coupler the locking mechanism including amovable locking element, biasing means adapted to bias the lockingelement to move in a first direction and an operator arranged to movethe locking element against the bias of the biasing means, the lockingelement has engagement means which, when the locking element is moved bythe biasing means in the first direction, is engagable with furtherengagement means coupled to a movable wedge element of a quick couplerto lock the wedge element from moving.

Broadly in a second aspect of the invention there is provided a quickcoupler that includes a movable wedge element, hydraulically operableoperating means to move the movable element, a movable locking element,biasing means adapted to bias the locking element to move in a firstdirection and an operator arranged to restrain the locking elementagainst movement in the first direction, the locking element hasengagement means which, when the locking element is permitted to bemoved by the biasing means in the first direction in the event offailure of hydraulic supply to the operating means, is engagable withthe movable element to lock the movable element against movement.

In a preferred form of the invention the biasing means is a mechanicalbiasing mechanism.

Preferably the mechanical biasing mechanism is at least one spring.

In a preferred form the operator is an hydraulically operated linearactuator.

In a preferred form of the invention the operator is operated byhydraulic pressure that from the hydraulic pressure source of theoperating means for the wedge element.

Preferably in one form of the invention the engagement means and furtherengagement means are both formed by a plurality of teeth that arearranged to intermesh.

Preferably movement of the locking element creates a compressive forcethat causes the teeth to positively mesh and remain meshed.

In a preferred form of the invention there is provided a stop that isengagable with the locking element when the locking element isrestrained by the operator to thereby create a clearance between theengagement means and further engagement means.

In one form the further engagement means are part of a catch componentthat is adapted to couple to the movable element.

In one form the locking element is movably coupled to a drive component.

In one form the locking element and drive component have inter-engagingdrive faces adapted translate movement of the locking element by thebiasing means into a lateral movement of the locking element. Preferablyin this form the locking element and drive component further includeslidingly engaged rails and guides.

In one form of the coupler there is a plurality of locking mechanisms.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following more detailed description of one embodiment of theinvention and its application to a quick coupler reference will be madeto the drawings which form part of this specification and in which:

FIG. 1 is a diagrammatic side elevation view in section of an hydraulicquick coupler incorporating a first embodiment of a locking mechanism inaccordance with the present invention,

FIG. 2 is an enlarged partial view of the arrangement shown in FIG. 1and illustrates the locking mechanism of FIG. 1 when the wedge elementof the quick coupler is moved to a wedging position,

FIG. 3 is a detail view of the juxtaposition of the teeth as shown inFIG. 2,

FIG. 4 is a view similar to FIG. 2 when the quick coupler wedge elementis moved (retracted) to a non wedging position during normal hydraulicoperation of the quick coupler,

FIG. 5 is a view similar to FIG. 4 but showing the locking mechanismlocking the wedge element upon an hydraulic failure occurring,

FIG. 6 is an isometric view of a coupler with a side removed to show thewedge and cylinder which incorporates a second embodiment of the lockingmechanism,

FIG. 7 is an exploded isometric view of the wedge, cylinder with secondembodiment of the locking mechanism as shown in FIG. 6,

FIG. 8 is an assembled view of the arrangement shown in FIG. 7 with thewedge fully retracted,

FIG. 9 is a similar view to FIG. 8 but with the wedge fully extended,

FIG. 10 is a sectioned isometric partial view showing the lockingmechanism components with the teeth fully apart (unlatched state), thesection having been taken a quarter way down the mechanism,

FIG. 11 is a view similar to FIG. 10 but with the teeth in a positionwhere any backward movement of the catch 23 will result ininter-engagement of the teeth 19 and 20 to cause the locking mechanismto become engaged so that the latch 11 is no longer able to move forwardagain into the unlatched state unless the catch 23 also moves forwardagain,

FIG. 12 is a view similar to FIG. 11 but showing the latch 11 havingmoved backwards by the bias spring 13 and outwards by the angled faces25 of the drive component 24 thereby having been moved into a latchedstate where the two sets of teeth 19 and 20 come into contact with oneanother,

FIG. 13 is a view similar to FIG. 12 showing the teeth 19 and 20 fullyengaged in the locked state,

FIG. 14 is an isometric sectioned view of components of the lockingmechanism as shown in FIGS. 10 to 13 but with the section having beentaken at the level of the upper surface of the biasing spring 13,

FIG. 15 is a view similar to FIG. 14 but with the section taken belowthe biasing spring 13,

FIG. 16 is a view similar to FIG. 15 but with the latch 11 shown biasedforward into the locked state,

FIG. 17 is an isometric view of the latch 11 and drive component 20showing the latch in the unlatched state,

FIG. 18 is a view similar to FIG. 17 but with the latch 11 in theengaged (locked) state,

FIG. 19 is a further sectioned view (taken at the level of FIG. 14)which shows the latch 11 moved forward by the biasing spring 13 into theengaged (locked) state and showing a clearance between a releaseactuator 26 of operator 12 and the latch 11,

FIG. 20 is a view similar to FIG. 19 but with the release actuator 26having been moved into contact with the latch 11,

FIG. 21 is a view similar to FIG. 20 but with the release actuator 26having moved the latch 11 backwards against the bias of the spring 13,and

FIG. 22 is a further view similar to FIG. 21 but with the releaseactuator fully extended so as to have moved the latch 11 fully backwardsinto the unlatched state.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

According to the invention the locking mechanism engages and locks thewedge tongue against movement immediately if there is a failure ofhydraulic pressure to the quick coupler so that the wedge tongue isprevented from any movement that may result in release of the mountingpoint(s) of an attachment mounted by the quick coupler.

Referring firstly to FIG. 1 there is shown a known form of quick couplerA made by our company and a first embodiment of the locking mechanism 10of the present invention when incorporated in the quick coupler. Thequick coupler A is operated hydraulically by the hydraulics of themachine to which the coupler is attached. The body B of the coupler hasmounting points C whereby the coupler is attached to say the arm of anexcavator (not shown).

The body B has a hook shaped part D into which one of the mounting pinsof an attachment (not shown) engages. Another mounting pin of theattachment locates in the recess E. An hydraulically powered wedgeelement or tongue F (hereinafter “wedge F”) is extendible to capture theattachment mounting pin in the recess E whereby the attachment iscoupled to the coupler A in its working position.

Thus if the hydraulic power to the coupler A fails the wedge F canretract which will enable release of the mounting pin from the recess Eto occur. If the other pin in hook shaped part D is not retained inposition the attachment can fall from the excavator arm. If the pin inthe hook shaped part D is, however, retained (by say our I Lock deviceas described and claimed in our New Zealand patent specification552294/546893) then the attachment will not fall completely off thecoupler A but will swing down on the pin in hook shaped part D.

In the form of coupler A shown in FIG. 1 the wedge F is part of anoperating means formed by hydraulic cylinder G which controls theextension and retraction of the wedge F. This is only one example of theform that the cylinder G and wedge F arrangement may take.

In the illustrated form of the coupler A the locking mechanism 10 isintegrated into the cylinder G/wedge F interface, however, this is onlyone example of how the locking mechanism of the present invention may beincorporated into a quick coupler. A further embodiment will bedescribed later with reference to FIGS. 6 to 22.

Referring now to FIG. 2 (and its associated detail drawing in FIG. 3)the locking mechanism 10 includes a locking element 11 (hereinafter“latch 11”), an operator 12 preferably in the form of a linear actuator(e.g. hydraulic cylinder) and a mechanical biasing element 13 preferablyin the form of e.g. a spring. The cylinder 12 is arranged to be operableby the machine hydraulics when the wedge F is retracted (see FIG. 4).The mechanical biasing mechanism biases the latch 11 into movement in afirst direction that is indicated by the letter X.

The latch 11 is substantially wedge shaped. A surface of the latch 11and a surface fixed in relation to the coupler body B form a slidinginterface 14 that will hereinafter be described in more detail. Thelatch 11 has a fixed surface 16 against which the cylinder can act. Thusin the first preferred embodiment as illustrated in FIGS. 1 to 5 ashoulder 15 provides the surface 16 with which the cylinder 12 isengagable.

One end of the spring biasing element 13 is located in a pocket (bore)17 in the latch 11. The other end of spring 13 engages against a fixedsurface 18.

A surface of the latch 11 that forms one side of the interface 14 isprovided with teeth or serrations 19 (hereinafter “teeth 19”) which arelocated opposite to, and are inter-engagable with, teeth or serrations20 (hereinafter “teeth 20”) that are coupled to the wedge F of thecoupler (see detail in FIG. 3). The teeth 20 can be part of an element(as described in the second embodiment) that is attachable to some partof the wedge F or the wedge operating cylinder G. However, theconnection of teeth 20 to the wedge F is achieved is not important tothe invention the primary criteria being that the teeth 20 move with thewedge F.

The detail drawing forming part of FIG. 3 shows the preferredconfiguration of the teeth sets 19 and 20. They can however, takedifferent forms provided they achieve the functional parameters as willherein after become apparent.

The teeth sets 19 and 20 are such that when the wedge F is moved(extended) into its operative wedging position the teeth 20 ride overthe teeth 19 due to the contact angle. The detail drawing of FIG. 3shows the teeth sets 19 and 20 when teeth 20 ride over the teeth 19. Thelatch 11 is free to move against the tension of spring 13 as the wedge Fis extended so that the teeth 19 and 20 ride over one another so thatthe latch 11 does not inhibit the extension of the wedge F.

When the wedge F has moved into its extended position the spring 13drives the latch 11 in direction X to ensure that the teeth 19 and 20engage and thus lock the wedge F in its extended position.

Under normal operating conditions the controls for the coupler areoperated to cause the wedge F to retract. Consequently hydraulicpressure is applied to the retract side of the double acting cylinder Gwhich simultaneously applies pressure to operator 12. The operator 12thus extends the release actuator 26 and applies pressure to surface 16of shoulder 15 which causes latch 11 to move against the pressure of thebiasing spring 13 i.e. in the direction indicated by the letter Y.

In the preferred arrangement as illustrated in FIGS. 1 to 5 of thedrawings the latch 11 comes into contact with a stop which convenientlyis formed by surface 18. When the latch 11 is against stop 18 aclearance (indicated by the letter Z) is formed between the teeth 19 and20. This ensures that the wedge F can freely retract (FIG. 3).

However, if at any time there is a failure in hydraulic pressure to thecoupler (which will remove pressure to wedge cylinder G) and wedge F isno longer held in its operative (extended) position by double actingcylinder G the bias spring 13 continues to drive the locking member indirection X along the sliding interface 14 and the resultant compressiveload in the direction of arrow 21 will cause teeth 19 and 20 to remainmeshed thereby continuing to lock the wedge F in its extended position.

As a result the wedge F is prevented from retracting in the direction ofarrow 22 thereby ensuring that despite the hydraulic failure the wedge Fretains the attachment pin in the recess E.

The locking mechanism 10 therefore locks the wedge F in its extendedposition and this locking effect is not lost upon an occurrence ofhydraulic supply failure.

Due to the number of teeth over which the load is transferred back tothe operator 12 and the compressive loading created due to the slideangle, teeth 19 and 20 may be relatively small which means backlash inthe mechanism is very small and effectively creates infinitely variablelocking positions. As a result the wedge F will be locked irrespectiveof what extended position the wedge F takes. Also the teeth 20 meshacross all or substantially all of teeth 19.

With the type of coupler illustrated in FIG. 1 the position of thelocking mechanism between the coupler wedge cylinder G and the wedgeinterface means that it is possible to create retro-fit kits forexisting coupler products in the market. These kits can be fitted in thefield. The skilled person will therefore appreciate that retro-fit kitscan be made for not only the coupler type illustrated and describedherein.

FIGS. 6 to 22 illustrate a second embodiment of the locking mechanism ofthe invention. One difference between the first and second embodimentsis that in the second embodiment there are preferably (as shown) twolocking mechanisms (one either side of the cylinder G and wedge F)rather than the single mechanism below the wedge F.

Components of the second embodiment that correspond with those of thefirst embodiment are, for convenience, indicated by the same referencenumerals.

FIG. 6 shows the coupler A but with one side plate component of the bodyB removed to reveal the hydraulic cylinder G and wedge F. It also showsthe locking mechanism 10 but this is better seen in FIG. 7 andsubsequent drawings.

FIG. 7 illustrates how the teeth/serrations 20 (hereinafter “teeth 20”)are part of a catch plate component (“catch”) 23 that is fastened bysuitable mechanical fasteners to a rebated inner surface 27 of the leg28 of a bifurcated section of the wedge F. As shown there is a lockingmechanism 10 associated with each leg 28 of the wedge F.

Similarly there is associated with a mounting recess 29 at each side ofthe cylinder C a drive component 24 and a latch 11. As shown latch 11has teeth/serrations 19 (i.e. teeth 19).

Thus as described above there are two locking mechanisms 10 in thesecond embodiment but the following description will, for convenience,primarily concentrate on the construction and operation of only one ofthe locking mechanisms 10.

FIG. 7 also shows how there is a pair of operators 12 with associatedactuators 26 mounted in either side of housing 30 so that each operator12 can work on a respective latch 11 of the two locking mechanisms 10.

FIGS. 10 to 13 are sectioned views with the section level beingsubstantially a quarter way down the cylinder G. FIG. 10 shows thelocking mechanism components 11, 23 and 24 with the teeth 19 and 20fully apart (unlatched state). The clearance Z mentioned in the firstembodiment is also shown. A large serrated part of the latch 11 mesheswith the corresponding serrated part of the drive component 24 to form aseries of drive faces 31 and 32 and stop faces 33 and 34 with a end stopface 18 (see FIGS. 11 and 12) being formed by an end wall of themounting recess 29.

As is apparent from FIGS. 14 and 19 to 22 the bias spring 13 is locatedin pocket 17 in the latch 11 and this acts against stop face 34′.

The controlled longitudinal and lateral movement of latch 11 by thedrive component 24 is further enhanced by the drive component 24 havingangled guide rails 35 and 36 that engage with guide slots 37 and 38 inthe latch 11 (see for example FIGS. 14 to 16). These rails 35 and 36align with the latch plate slots 37 and 38 and assist the releaseprocess when the release actuator 26 pushes on the back face 39 of thelatch 11. The slot face slides on the rail thereby pulling the latch 11back in a controlled line with the drive faces 31 and 32 and bias spring13. These also assist with a ratchet effect that occurs when the wedge Fis extended, thereby ensuring that the movement of latch 11 is paralleland consistent between each of the sets of teeth 19 and 20.

FIGS. 17 and 18 show how the latch 11 can move from the “retracted”state (unlatched) of FIG. 17 to the “extended” state (engaged) of FIG.18 and further shows the portion of latch 11 with slots 37 and theirinteraction with rails 35.

FIGS. 19 to 22 show a section taken at a level that shows the spring 13in the pocket 17. These drawings also show how the actuator 26 of theoperator 12 can engage with surface 39 of latch 11 and drive the latch11 back into the unlatched state. In the preferred form the releaseactuator 26 has its own return spring 40 (see FIG. 7) which retracts theactuator 26 away from the latch 11 contact face 39 (FIG. 19) when itshydraulic pressure is released. This ensures that the bias spring 13only has to effect the movement of latch 11.

The second embodiment operates in the same manner as the firstembodiment. Thus, for example, FIG. 10 shows the latch 11 moved to itsfully retracted (unlatched) position where the clearance Z allows thewedge F to be moved without any interference i.e. from teeth 19 and 20making contact.

FIG. 11 shows the teeth 19 and 20 in a position where any backwardmovement of the catch 23 will result in inter-engagement of the teeth 19and 20 to thereby cause the locking mechanism 10 to become engaged sothat the latch 11 is no longer able to move forward again into theunlatched state unless the catch 23 also moves forward again.

FIG. 12 shows the latch 11 having moved backwards by the bias spring 13and outwards by the angled faces 31 of the drive component 24 therebyhaving been moved into a latched state where the two sets of teeth 19and 20 come into contact with one another.

FIG. 13 shows the teeth 19 and 20 fully engaged in the locked state. Anymovement of the catch 23 backwards causes the latch 11 to drive furtherback on the drive component 24 which locks the wedge F in place.

There are three main components that make up the locking mechanism,latch 11, drive component 20 and the catch 23, plus spring 13 being abias mechanism. The drawings show their assembly configuration withinthe illustrated coupler, but could be varied in other sized couplers.These parts are designed as such to be serviceable parts, but could beintegrated within the coupler in which they are assembled.

A technical aspect of the invention is the relationship between angle ofmovement of the latch 11 on the drive component 24 and the angle of thesets of teeth 19 and 20. The latch 11 in the preferred form moves at anangle of 30 degrees while the teeth 19,20 angle is set at 45 degrees.During operation what happens is that when the front of the teeth 19 and20 are in contact with each other, they are sitting in the latchedstate. If after this the catch 23 moves backwards enough to shift intothe engaged state (an engaged state being the point where the two setsof teeth 19 and 20 are permanently interlocked) they are no longer ableto be separated due to the cross over angle relationships. This leavesthe locking mechanism 10 in an engaged state and separation is unable tohappen until the catch 23 is moved forwards out of the way. This stateis shown by FIG. 11.

The locking mechanism of the present invention is operable in the eventof hydraulic failure to ensure an attachment mounted by the quickcoupler is retained in a working position on the coupler.

The present invention has been described and illustrated by way of aspecific embodiments. It is not the intention of the Applicant torestrict or in any way limit the scope of the invention to such detail.For example, the coupler illustrated herein is only one type of couplerwith which the locking mechanism can be used. Also the locking mechanismcan be provided in retro fit kits to be fitted to couplers other thatthe type illustrated in the drawings and described herein.

Another example of how the invention can be realised in a differentembodiment is that the release actuator does not need to behydraulically operated. The skilled person will for example readilyunderstand that the invention is relevant to a hose-less hydraulic-lesscoupler and in such an arrangement, as well as a coupler of the typedescribed herein, other means for releasing can be employed.

Additional advantages and modifications will be readily apparent tothose skilled in the art. Therefore, the invention in its broaderaspects is not limited to the specific details, representative means ofmanufacture and method, and illustrative examples shown and described.Accordingly, departures may be made from such details without departurefrom the spirit or scope of the Applicant's general inventive concept.

1. A locking mechanism for a quick coupler the locking mechanismincluding a movable locking element, biasing means adapted to bias thelocking element to move in a first direction and an operator arranged tomove the locking element against the bias of the biasing means, thelocking element has engagement means which, when the locking element ismoved by the biasing means in the first direction, is engagable withfurther engagement means coupled to a movable wedge element of a quickcoupler to lock the wedge element from moving.
 2. A locking mechanism asclaimed in claim 1 wherein the biasing means is a mechanical biasingmechanism.
 3. A locking mechanism as claimed in claim 2 wherein themechanical biasing mechanism is at least one spring.
 4. A lockingmechanism as claimed in claim 2 for wherein the operator is anhydraulically operated linear actuator.
 5. A locking mechanism asclaimed in claim 4 wherein the operator is operated by hydraulicpressure from the hydraulic pressure source of the operating means forthe wedge element.
 6. A locking mechanism as claimed in claim 1 whereinthe engagement means and further engagement means are both formed by aplurality of teeth that are arranged to intermesh.
 7. A lockingmechanism as claimed in claim 6 wherein movement of the locking elementcreates a compressive force that causes the teeth to positively mesh andremain meshed.
 8. A locking mechanism as claimed in any one of thepreceding claims claim 6 further including a stop that is engagable withthe locking element when the locking element is restrained by theoperator to thereby create a clearance between the engagement means andfurther engagement means.
 9. A locking mechanism as claimed in precedingclaims claim 6 wherein the further engagement means are part of a catchcomponent that is adapted to couple to the movable element.
 10. Alocking mechanism as claimed in claim 6 wherein the locking element ismovably coupled to a drive component.
 11. A locking mechanism as claimedin claim 10 wherein the locking element and drive component haveinter-engaging drive faces adapted translate movement of the lockingelement by the biasing means into a lateral movement of the lockingelement.
 12. A locking mechanism as claimed in claim 11 wherein thelocking element and drive component further include slidingly engagedrails and guides.
 13. A quick coupler that includes a movable element,operating means to move the movable element, a movable locking element,biasing means adapted to bias the locking element to move in a firstdirection and an operator arranged to restrain the locking elementagainst movement in the first direction, the locking element hasengagement means which, when the locking element is permitted to bemoved by the biasing means in the first direction in the event offailure of hydraulic supply to the operating means, is engagable withthe movable element to lock the movable element against movement.
 14. Aquick coupler as claimed in claim 13 wherein the biasing means is amechanical biasing mechanism.
 15. A quick coupler as claimed in claim 13wherein the engagement means and further engagement means are bothformed by a plurality of teeth that are arranged to intermesh, whereinmovement of the locking element creates a compressive force that causesthe teeth to positively mesh and remain meshed.
 16. A quick coupler asclaimed in claim 15 further including a stop that is engagable with thelocking element when the locking element is restrained by the operatorto thereby create a clearance between the engagement means and furtherengagement means.
 17. A quick coupler as claimed in claim 16 wherein thefurther engagement means are part of a catch component that is adaptedto couple to the movable element.
 18. A quick coupler as claimed inclaim 15 wherein the locking element is movably coupled to a drivecomponent.
 19. A quick coupler as claimed in claim 15 wherein theoperator is an hydraulically operated linear actuator that is operatedby hydraulic pressure from the hydraulic pressure source of theoperating means for the movable element.
 20. A quick coupler as claimedin claim 15 wherein there is a plurality of locking mechanisms. 21.(canceled)
 22. (canceled)